but the former kate middleton, the duchess of cambridge, is now not even 12 weeks along and her morning sickness is so severe she's now in the hospital. our senior medical correspondent, elizabeth cohen, is on the story for us. elizabeth, how often do women end up in the hospital with morning sickness during the first trimester? >> any woman can tell you, morning sickness is quite common, it happens to a lot of women. a relatively small percentage end up in the hospital. what's also interesting is morning sickness doesn't just happen in the morning. it can go on all day long. some women when they get to that 13, 14-week mark, it magically goes away. other women experience it all pregnancy long. >> what's the treatment? >> the treatment is, you put someone in the hospital if it's really severe because you need to get the medicines and nutrition and fluids iv. if the woman can't keep anything down, you give them anti-nausea medications iv. it has to be iv because she's throwing everything up. >> let's hope the best for kate, the former kate middleton, the duchess of cambridge. thanks very